I'm a huge fan of Stephen King and have been for many years but I've hated the majority of adaptations of his work. Not because they don't stay true to the books but because sometimes they stay too true and it just doesn't work. There is a huge difference between a book and a screenplay so doing a word for word copy of a book, especially a King book, just doesn't work on the screen. Thankfully with Mr Mercedes this hasn't happened. The characters are there, the plot is there but there are differences and I'm glad there are. Brendan Gleeson is a great choice for Bill and the production doesn't have that cheap feel that a lot of King adaptations have (The Mist TV series, Under the Dome, The Shining mini series to name but a few). I'm two episodes in and I'm hooked. I only hope they don't let it ramble on beyond the source material and spoil it as that would be a real shame.
